Danielle Waterman bursts through the Spanish defence on her way to a try. Photograph: Jordan Mansfield/Getty Images

England face Canada on Saturday in a Pool A decider after enjoying their second huge victory in four days, before their group rivals overwhelmed Samoa. The flanker Marlie Packer scored two of their six tries in a dominant display that leaves her head coach, Gary Street, with a selection dilemma in the back row.

Spain were more organised than Samoa had been four days previously, keeping their shape apart from a 10-minute spell at the start of the second-half when England scored three tries, but their skill level was low and they were laboured in their passing, uncertain in their handling and deficient at the lineout, where they wasted several good attacking positions poor throws.

England, who had the clear beating of their opponents from the outset, were patient, sticking to a plan which involved kicking for territory and driving through the forwards, having been more unstructured against Samoa. They led 17-0 at the interval before raising their intensity after the break. Their one disappointment was conceding their first try of the competition 14 minutes from the end when Marina Bravo finished off Spain’s one move of note.

Spain felt insulted that their opponents made a raft of personnel changes from the Samoa game but the gulf in quality was evident from the outset. Indeed England were forced to make a further switch when winger Lydia Thompson strained a hamstring in the warm-up. Claire Allan filled her position from the centre, with Emily Scarratt moving off the bench into the midfield and kicking seven goals from seven attempts.

“Our plan was to see all 26 players in action in the first two matches,” said Street. “We started slowly against Spain, knowing we would have to be patient. We got ourselves into good positions and space eventually came our way. We will have some fresh legs to come into contention for Canada, but there will be tough choices ahead of what will be a very difficult game.”

The wing Kay Wilson gave England the lead when she outpaced three defenders to reach Ceri Large’s chip to the line and, after Scarratt had kicked a penalty, Danielle Waterman shrugged off Bravo’s challenge and stepped away from the full-back Maria Cabane to score under the posts.

Allan secured the bonus point nine minutes into the second half, supporting Large’s break after the replacement prop Laura Keates had been at the bottom of a 15-metre driving maul for England’s third try. When Packer scored her first try, shrugging off five defenders on a powerful, arcing run, England looked likely to surpass the 65 points they had scored against Samoa.

Spain, though, rallied and Bravo’s try was reward for a refusal to buckle, but even if England had the final word with the last play of the game when a driving maul led to another powerful driving maul earned Packer grabbing her brace.

“We will look at our performance and see what went well and what areas we need to tweak ahead of Canada,” said the England captain, Sarah Hunter. “We lost our way at times against Samoa and we knew Spain would come at us. We went through the phases, kept our shape and played the game in the right areas.”